1 Overview

Sample selection protocol:

  1. Stationary trips

  2. Complete checklists (report all species)

  3. Drop duplicates from group trips.

  4. Drop trips with 1 bird

  5. Duration between 5-240 mins

Overall Notes

  1. Results are sensitive to sample selection criteria (num cities, number days pre/post, home, lockdown date)

  2. We select cities first, and then users. This gives us the same users in each pre/post period (in 2020) with the caveat that users mobility is limited to the top X cities.

  3. Quite few people take stationary trips pre-lockdown.

1.1 Birdwatching Activity in All Cities

Summary Stats for 2020 for all users. Number of users is the counts unique user ID’s on a given day.

1.2 Birdwatching Activity in Top 4 Cities

Number of users is the count of unique user ID’s on a given day. Stationary trips are uncommon pre-COVID.

1.3 Top 20 Cities

Subset of top 20 cities in which users meeting participation constraint are present.

Subset of Top 20 Cities where power users present
COUNTY STATE POP_DENSITY
North East Delhi Delhi 36155.2258
Central Delhi Delhi 27729.5238
East Delhi Delhi 27132.4762
Chennai Tamil Nadu 26552.7543
Kolkata West Bengal 24306.4541
Mumbai Suburban Maharashtra 20979.7354
Mumbai Maharashtra 19652.2994
West Delhi Delhi 19563.4077
South Delhi Delhi 11060.4413
South West Delhi Delhi 5446.4561
Bangalore Karnataka 4381.3985
New Delhi Delhi 4057.2571
Haora West Bengal 3306.0866
North 24 Parganas West Bengal 2444.9880
Faridabad Haryana 2442.2848
South 24 Parganas West Bengal 819.4740
Hyderabad Telangana 706.8919

1.4 Pre-Post Lockdown Statistics

This table shows birdwatching activity among users who took at least 2 trips before and after lockdown. Mar 22 trips are dropped.
All Cities
PREPOST Num. Trips Num. Cities Num. Users Num. Species
Before 3326 179 336 667
After 10160 135 336 602
Top 20
PREPOST Num. Trips Num. Cities Num. Users Num. Species
Before 662 17 67 205
After 2014 15 67 215

1.5 Trip Statistics

This table shows trip statistics before and after lockdown among users meeting the participation constraint.

All Cities
PREPOST Trip Length Mean Species Richness Median Species Richness
Before 25.05201 12.20806 10
After 22.27874 12.31033 11
Top 20
PREPOST Trip Length Mean Species Richness Median Species Richness
Before 22.05589 10.43958 9
After 23.33515 12.25223 11

1.6 Marginal Species by city

Marginal species are species observed after lockdown which were not observed before lockdown. To implement: in each city, obtain list of species before and after lockdown observed by users meeting participation cosntraint. Extract species in “after” list not in “before” list.

COMMON.NAME SCIENTIFIC.NAME COUNTY
falcon sp. Falco sp. Kolkata
swift sp. Apodidae sp. Kolkata
white egret sp. Ardea/Egretta/Bubulcus sp. Kolkata
Little Egret Egretta garzetta Kolkata
Common Kingfisher Alcedo atthis Kolkata
Barn Owl Tyto alba Kolkata
Fulvous-breasted Woodpecker Dendrocopos macei Kolkata
Asian Openbill Anastomus oscitans Kolkata
Paddyfield Pipit Anthus rufulus Kolkata
Gray-headed Swamphen Porphyrio poliocephalus Kolkata
Scaly-breasted Munia Lonchura punctulata Kolkata
Rufous Woodpecker Micropternus brachyurus Kolkata
Zitting Cisticola Cisticola juncidis Kolkata
Oriental Honey-buzzard Pernis ptilorhynchus Kolkata
Eurasian Moorhen Gallinula chloropus Kolkata
Red-breasted Parakeet Psittacula alexandri Kolkata
Spotted Owlet Athene brama South 24 Parganas
Taiga Flycatcher Ficedula albicilla South 24 Parganas
Red-whiskered Bulbul Pycnonotus jocosus South 24 Parganas
Bengal Bushlark Mirafra assamica South 24 Parganas
Blyth’s Reed Warbler Acrocephalus dumetorum South 24 Parganas
Shikra Accipiter badius South 24 Parganas
Indian Golden Oriole Oriolus kundoo South 24 Parganas
Barn Owl Tyto alba South 24 Parganas
Rufous Woodpecker Micropternus brachyurus South 24 Parganas
Indian White-eye Zosterops palpebrosus West Delhi
Laughing Dove Streptopelia senegalensis West Delhi
Rose-ringed Parakeet Psittacula krameri West Delhi
prinia sp. Prinia sp. West Delhi
Jungle Babbler Turdoides striata West Delhi
Black Drongo Dicrurus macrocercus West Delhi
Yellow-eyed Babbler Chrysomma sinense Bangalore
Indian Silverbill Euodice malabarica Bangalore
swift sp. Apodidae sp. Bangalore
ibis sp. Threskiornithidae sp. (ibis sp.) Bangalore
Common Hawk-Cuckoo Hierococcyx varius Bangalore
parakeet sp. Psittaciformes sp. (parakeet sp.) Bangalore
Greater Spotted Eagle Clanga clanga Bangalore
Red-rumped Swallow Cecropis daurica Bangalore
Ashy Woodswallow Artamus fuscus Bangalore
Pied Kingfisher Ceryle rudis Bangalore
Eurasian Spoonbill Platalea leucorodia Bangalore
bird sp. Aves sp. Bangalore
cormorant sp. Phalacrocoracidae sp. Bangalore
stork sp. Ciconiidae sp. Bangalore
Lonchura sp. Lonchura sp. Bangalore
Oriental Honey-buzzard Pernis ptilorhynchus Bangalore
Garganey Spatula querquedula Bangalore
Black-rumped Flameback Dinopium benghalense Bangalore
White-naped Woodpecker Chrysocolaptes festivus Bangalore
Blue-throated Flycatcher Cyornis rubeculoides Bangalore
Blue-faced Malkoha Phaenicophaeus viridirostris Bangalore
prinia sp. Prinia sp. Bangalore
flowerpecker sp. Prionochilus/Dicaeum sp. Bangalore
Red-naped Ibis Pseudibis papillosa Bangalore
bee-eater sp. Merops sp. Bangalore
eagle sp. Accipitridae sp. (eagle sp.) Bangalore
duck sp. Anatinae sp. Bangalore
Eurasian Coot Fulica atra Bangalore
Blyth’s Pipit Anthus godlewskii Bangalore
Black-naped Monarch Hypothymis azurea Bangalore
Indian Blue Robin Larvivora brunnea Bangalore
Indian Pitta Pitta brachyura Bangalore
Black/Ashy Drongo Dicrurus macrocercus/leucophaeus Bangalore
Yellow Bittern Ixobrychus sinensis Bangalore
Indian Silverbill Euodice malabarica Mumbai
Rosy Starling Pastor roseus Mumbai
Indian Robin Copsychus fulicatus Mumbai
Jungle Babbler Turdoides striata Mumbai
Phylloscopus sp. Phylloscopus sp. Mumbai
Indian Cormorant Phalacrocorax fuscicollis Mumbai
Asian Openbill Anastomus oscitans Mumbai
Shikra Accipiter badius Mumbai
Little Stint Calidris minuta Mumbai
Brahminy Kite Haliastur indus Mumbai
wagtail sp. Motacilla sp. Mumbai
Ashy Woodswallow Artamus fuscus North 24 Parganas
Lesser Whistling-Duck Dendrocygna javanica North 24 Parganas
Little Swift Apus affinis North 24 Parganas
Indian Peafowl Pavo cristatus East Delhi
White-throated Kingfisher Halcyon smyrnensis East Delhi
Green Bee-eater Merops orientalis East Delhi
Rosy Starling Pastor roseus East Delhi
Striated Babbler Turdoides earlei East Delhi
Black Redstart Phoenicurus ochruros East Delhi
Red-whiskered Bulbul Pycnonotus jocosus East Delhi
White Wagtail Motacilla alba East Delhi
Bank Myna Acridotheres ginginianus East Delhi
Great Cormorant Phalacrocorax carbo East Delhi
passerine sp. Passeriformes sp. East Delhi
Green Sandpiper Tringa ochropus East Delhi
Indian Pond-Heron Ardeola grayii East Delhi
Hume’s Warbler Phylloscopus humei East Delhi
Greater Coucal Centropus sinensis East Delhi
Gray-breasted Prinia Prinia hodgsonii East Delhi
Red-breasted Flycatcher Ficedula parva East Delhi
Woolly-necked Stork Ciconia episcopus East Delhi
Red-naped Ibis Pseudibis papillosa East Delhi
Shikra Accipiter badius East Delhi
Indian Cormorant Phalacrocorax fuscicollis East Delhi
Egyptian Vulture Neophron percnopterus East Delhi
swift sp. Apodidae sp. East Delhi
Little Swift Apus affinis East Delhi
Indian Golden Oriole Oriolus kundoo East Delhi
Gray Heron Ardea cinerea East Delhi
ibis sp. Threskiornithidae sp. (ibis sp.) East Delhi
Indian Spotted Eagle Clanga hastata East Delhi
Purple Heron Ardea purpurea East Delhi
Indian Spot-billed Duck Anas poecilorhyncha East Delhi
Little Egret Egretta garzetta East Delhi
Lesser Whitethroat Sylvia curruca East Delhi
Indian Golden Oriole Oriolus kundoo Mumbai Suburban
Laughing Dove Streptopelia senegalensis Mumbai Suburban
Indian Robin Copsychus fulicatus Mumbai Suburban
parakeet sp. Psittaciformes sp. (parakeet sp.) South Delhi
Rosy Starling Pastor roseus South Delhi
crow sp. Corvus sp. (crow sp.) South Delhi
Large Gray Babbler Turdoides malcolmi South Delhi
House Sparrow Passer domesticus South Delhi
Indian Robin Copsychus fulicatus South Delhi
Spotted Dove Streptopelia chinensis Chennai
sunbird sp. Nectariniidae sp. (sunbird sp.) Chennai
white egret sp. Ardea/Egretta/Bubulcus sp. Chennai
owl sp. Strigiformes sp. Chennai
Orange-headed Thrush Geokichla citrina Chennai
Red-whiskered Bulbul Pycnonotus jocosus Chennai
Western Yellow Wagtail Motacilla flava Chennai
Indian Silverbill Euodice malabarica Chennai
Pied Kingfisher Ceryle rudis Chennai
House Sparrow Passer domesticus Chennai
Plain Prinia Prinia inornata Chennai
Asian Openbill Anastomus oscitans Chennai
Asian Pied Starling Gracupica contra Chennai
Ashy Prinia Prinia socialis Chennai
Black Bittern Ixobrychus flavicollis Chennai
tern sp. Sterninae sp. Chennai
swift sp. Apodidae sp. Chennai
Little Swift Apus affinis Chennai
Oriental Honey-buzzard Pernis ptilorhynchus South West Delhi
Little Swift Apus affinis South West Delhi
old world warbler sp. Passeriformes sp. (Old World warbler sp.) South West Delhi
Egyptian Vulture Neophron percnopterus South West Delhi
Indian Golden Oriole Oriolus kundoo South West Delhi
Long-tailed Shrike Lanius schach South West Delhi
Common Chiffchaff Phylloscopus collybita South West Delhi
Short-toed Snake-Eagle Circaetus gallicus South West Delhi
Gray Heron Ardea cinerea South West Delhi
Great Cormorant Phalacrocorax carbo South West Delhi
Blyth’s Reed Warbler Acrocephalus dumetorum South West Delhi
Brown Rock Chat Oenanthe fusca South West Delhi
Rose-ringed Parakeet Psittacula krameri North East Delhi
Brown-headed Barbet Psilopogon zeylanicus North East Delhi
Asian Koel Eudynamys scolopaceus North East Delhi
Coppersmith Barbet Psilopogon haemacephalus North East Delhi
Large Gray Babbler Turdoides malcolmi North East Delhi
Rock Pigeon Columba livia North East Delhi
Alexandrine Parakeet Psittacula eupatria Faridabad
Common Myna Acridotheres tristis Faridabad
Rock Pigeon Columba livia Faridabad
Black Kite Milvus migrans Faridabad
Asian Koel Eudynamys scolopaceus Faridabad
Asian Pied Starling Gracupica contra Faridabad
Rose-ringed Parakeet Psittacula krameri Faridabad
Indian White-eye Zosterops palpebrosus Faridabad
Laughing Dove Streptopelia senegalensis Faridabad
Brown-headed Barbet Psilopogon zeylanicus Faridabad
Coppersmith Barbet Psilopogon haemacephalus Faridabad
Yellow-footed Green-Pigeon Treron phoenicopterus Faridabad
Cattle Egret Bubulcus ibis Faridabad
Eurasian Collared-Dove Streptopelia decaocto Faridabad
Red-whiskered Bulbul Pycnonotus jocosus Faridabad
Shikra Accipiter badius Faridabad
Indian Gray Hornbill Ocyceros birostris Faridabad
White-throated Kingfisher Halcyon smyrnensis Faridabad
Blyth’s Reed Warbler Acrocephalus dumetorum Faridabad
Green Bee-eater Merops orientalis Faridabad
Large-billed Crow Corvus macrorhynchos Hyderabad
Tickell’s Blue Flycatcher Cyornis tickelliae Hyderabad
Cattle Egret Bubulcus ibis Hyderabad
Thick-billed Flowerpecker Dicaeum agile Hyderabad
Thick-billed/Pale-billed Flowerpecker Dicaeum agile/erythrorhynchos Hyderabad
swallow sp. Hirundinidae sp. Hyderabad
Indian Peafowl Pavo cristatus Hyderabad
Rufous Treepie Dendrocitta vagabunda Hyderabad
Indian Robin Copsychus fulicatus Hyderabad
Dusky Crag-Martin Ptyonoprogne concolor Hyderabad
Rosy Starling Pastor roseus Hyderabad
White-browed Wagtail Motacilla maderaspatensis Hyderabad
Barn Swallow Hirundo rustica Hyderabad
Indian Pond-Heron Ardeola grayii Hyderabad
Indian Gray Hornbill Ocyceros birostris Hyderabad
diurnal raptor sp. Accipitriformes/Falconiformes sp. Hyderabad
parakeet sp. Psittaciformes sp. (parakeet sp.) Hyderabad
Glossy Ibis Plegadis falcinellus Hyderabad
Little Egret Egretta garzetta Hyderabad
River Tern Sterna aurantia Hyderabad
Gray-bellied Cuckoo Cacomantis passerinus Hyderabad
Western Yellow Wagtail Motacilla flava Hyderabad
Gray Wagtail Motacilla cinerea Hyderabad
Eurasian Kestrel Falco tinnunculus Hyderabad
Large-billed Leaf Warbler Phylloscopus magnirostris Haora
Barn Swallow Hirundo rustica Haora
Eurasian Collared-Dove Streptopelia decaocto Haora
Asian Palm-Swift Cypsiurus balasiensis Haora
White-throated Kingfisher Halcyon smyrnensis Haora
Jungle Babbler Turdoides striata Haora
Intermediate Egret Ardea intermedia Haora
Green-crowned Warbler Phylloscopus burkii Haora
Blue-throated Flycatcher Cyornis rubeculoides Haora
Large-billed Crow Corvus macrorhynchos Haora
Greater Coucal Centropus sinensis Haora
Cattle Egret Bubulcus ibis Haora
Asian Brown Flycatcher Muscicapa dauurica Haora
Rufous Treepie Dendrocitta vagabunda Haora
Greenish Warbler Phylloscopus trochiloides Haora

2 Event Study

We estimate:

\[ SR_{ijtd} = \sum_{e=-24, e\neq0}^{24} 1(t-LD=e)\beta_{e} + X_{ijdt} + \theta_{i} + \gamma_{t} + \epsilon_{ijtd}\] where \(SR_{ijtd}\) is species richness observed by user i on trip j on date t in district d. Each coefficient \(\beta_{e}\) captures species richness relative to the day of lockdown (LD). In the preferred specification, LD = March 24, 2020 and this date is normalized to zero and omitted so that it describes the reference period. If the timing of lockdown is exogenous to pre-period outcomes, then \(\beta_{e}\) should be zero for all \(e<0\).\(\theta_{i}\) is a user fixed effect and controls for observer bias, experience, and innate ability. Since users primarily remain in the same city before and after lockdown, we do not include a district fixed effect. \(\gamma_{t}\) are a set of temporal controls and include date fixed effects and hour fixed effects. \(X_{ijdt}\) is a vector of controls including trip duration and daily rainfall.

Note:

  1. We start seeing increases in species diversity post-lockdown when we narrow in on urban environments. As we increase number cities, this adds population-sparse places so the effect is dampned.

  2. Larger increases in post-lockdown species diversity as we increase the participation constraint (e.g. 10 days before/after curfew)

2.1 Species Distributions (Bangalore Only)

data: number of times each user sees each species before and after lockdown. interpretation: proportion of user base seeing different frequencies of species.

3 Difference-in-Difference

In this specification, we aim to estimate the difference in species richness per trip before and after lockdown, compared to same difference in 2019. In other words, we subtract the change in the pre-post period of 2019 (the counterfactual) from the 2020 lockdown effect to remove other determinants of species richness that are changing during the window.

To do this, we first select 2020 users with at least 2 trips before and after lockdown. Then we 2019 with the same criteria, using March 24, 2019 as the threshold date. These are different users but share similar characteristics.

Formally, we specify the following standard DID regression:

\[ SR_{ijdt} = \beta_{1} [Treatment_{t} \times Post_{t}] + \beta_{2} [Treatment_{t}] + \beta_{3}[Post_{t}] + X_{ijdt} + \mu_{d} + \gamma_{t} + \epsilon_{ijdt} \]

Where \(Treatment_{t}\) is a dummy for the year 2020 and \(Post_{t}\) is a dummy equal to one for observations after March 24th. \(\beta_{1}\) is the coefficient of interest and describes the change in species richness before and after March 19 in 2020 compared to the same difference in 2019. \(\beta_{2}\) describes the difference in the “before” groups (pre-intervention). \(\beta_{3}\) captures the time trend in the control (2019) group. \(X_{ijdt}\) is a vector of controls including trip duration and rainfall. \(\mu_{d}\) is a set of city fixed effects and \(\gamma_{t}\) is a set of temporal controls including date and hour fixed effects.

Diff-in-Diff Estimates
All Cities, 2 trips Top 20, 2 trips Top 20, 5 trips Top 20, 10 trips
Treat x Post 0.972*** 2.738*** 2.958*** 2.583***
(0.214) (0.376) (0.363) (0.382)
Duration 0.131*** 0.097*** 0.129*** 0.127***
(0.002) (0.004) (0.006) (0.006)
Post -0.664*** -1.765*** -1.622*** -1.176***
(0.233) (0.410) (0.404) (0.431)
Treatment -4.585* -12.122*** -11.747*** -8.233*
(2.464) (4.346) (4.390) (4.686)
Num.Obs. 19030 3723 2846 2422
R2 0.349 0.297 0.344 0.353
Adj.R2 0.340 0.293 0.339 0.348
AIC 123589.0 22322.0 16363.6 13847.6
BIC 125568.2 22490.0 16506.5 13963.4
Log.Lik. -61542.516 -11134.014 -8157.816 -6903.795
* p < 0.1, ** p < 0.05, *** p < 0.01